ASSOCIATIVE THICKENERS - THEIR ADSORPTION BEHAVIOR ONTO LATEXES AND THE RHEOLOGY OF THEIR SOLUTIONS

The interaction between an associative thickeners in solution and an a nionic surfactant has been studied with rheology and surface tension m easurements, Both a HEUR thickener and low molecular weight HMHEC thic kener interacted strongly with the surfactant. The addition of surfact ant leads in both cases to a reinforced transient network at low and m oderate levels of surfactant, whereas the structure is destroyed at hi gher levels. The HMHEC thickener was found more sensitive to high surf actant concentrations than the HEUR one. Surface tension measurements are complementary to the rheology studies and showed hydrophobic inter action between HEUR thickener and surfactant to be dominant over polye thylene oxide - surfactant interaction. Adsorption of thickener to lat ex was studied with monitoring of isotherms from depletion concentrati on, electrokinetic measurements and ellipsometry. The HEUR thickener u sed was found to adsorb more strongly to the latex than the surfactant in contrast to the HMHEC thickener. (C) 1997 Elsevier Science S.A.